Method and apparatus for treating wire

ABSTRACT

A method of treating wire, both coated and uncoated, and a wire drawing die which provide improved lubrication of the wire and a lower wire temperature during treatment than have heretofore been obtainable and resulting in a cold drawn wire product having greater tensile strength and core density, considerable increase in cohesive strength and significant improvement in ductility.

United States Patent 1191 [111 3,73, Godfrey et al. 51 @et. 9, 1973METHOD AND APPARATUS FOR 2,135,659 11/1938 Elfstrom 72/43 TREATING WIRE2,349,652 5/1944 Fenner 72/467 2,383,118 8/1945 Ferenci 72/467Inventors: Howard J- y, g o 3,157,274 11/1964 Kyle et al 72/274 StephenW. Homa, Trenton; Ronald J. Stott, Beverly, all of NJ. FOREIGN PATENTSOR APPLICATIONS [73] Assignee: CF & I Steel Corporation, Denver, 905,4959/1962 Great Britain 72/41 Colo.

. Primary Examiner-Charles W. Lanham [22} Flled' 1972 AssistantExaminerE. M. Combs [21] Appl. No.: 282,954 Att0rneyDean S. Edmonds etal.

Related US. Application Data [63] Continuation of Ser. No. 54,122, July13, 1970, [57] ABSTRACT abandoned.

A method of treatmg wire, both coated and uncoated, [52] CL 72/43 72/27472/467 and a wire drawing die which provide improved lubri- [51] IntB21c3/02 c 9/00 cation of the wire and a lower wire temperature dur-[58] Field of 72/41 44 45 ing treatment than have heretofore beenobtainable and resulting in a cold drawn wire product having greatertensile strength and core density, considerable [56] References Citedincrease in cohesive strength and significant improve- UNITED STATESPATENTS "lent dummy 1,582,434 4/1926 Simons 72/41 3 Claims, 2 DrawingFigures Bird/M01770 Jame/ran; EA'IR/M METHOD AND APPARATUS FOR TREATINGWIRE This application is a continuation, of application Ser. No. 54,122filed July 13, 1970, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention Production of colddrawn wire products.

2. Description of the Prior Art Fleischmann et al. U.S. Pat. No.3,080,962 relates to a complicated die system including three dies inseries for drawing aluminum coated wire. This three-die system providesa buildup in lubricant pressure (finely powdered soap) in the first two.dies so that the lubricant is forced into the thirdor actual wiredrawing die. Should the lubrication not be effective with coated wire,the aluminum or zinc coating will weld-to the die, and in the case ofuncoated material the wire will become overheated and scrape in the diethus destroying the smooth surface intended for the wire.

Fenner U.S. Pat. No. 2,349,652 discloses a wire drawing die having asmall entrance angle (3-% to 10) but it has not proved satisfactorybecause the die is not long enough to develop the necessary pressure inthe lubricant to force it between the wire and the die in thedeformation section. The length of the lubricating section has beenignored.

SUMMARY OF THE INVENTION According to applicant's method, wire of aselected diameter is passed through a reducing die having a lubricatingzone followed by a deforming or deformation zone. The wire iscontinuously drawn through a suitable lubricant, advantageously a drypowder, carrying the lubricant into the lubricating zone within which itis subjected to friction with the wire as it travels through anelongated space of sufficient length and adequate gradual reduction inthickness to cause the friction between the lubricant and the surface ofthe wire to develop sufficient pressure to force the lubricant inquantity between the wire and the die in the deforming zone.

The wire may be pulled through the die at moderate speeds of 500' or600' per minute but advantageously it is pulled through at speeds muchhigher, for example, from about 1,000' per minute to about 1,450 perminute, the wire travelling at these speeds through an elongatedlubricating zone in intimate contact with the dry powdered lubricantsuch as wire drawing soap and then through the deforming zone. Thelubricating zone has a wall which is only slightly spaced from the wireand which is constructed to press the lubricant against the wire as itmoves through this zone, the speed of the wire in cooperation with theslight spacing of the wall acting to feed the lubricant forward into andthrough the elongated lubricating zone and the deforming zone and alsoserving to retard movement of the lubricant in a direction opposite tothe forward movement of the wire.

The wall referred to is in the form of a frusto-conical passagewaythrough both the lubricating and the deforming zones, the included anglebetween the opposite sides of this frusto-conical passageway beingidentical throughout both the lubricating and deformation sections. Suchangle is from about 5 to about l0. The length of the lubricating zone orsection is several times the length of the deformation section, beingfrom about 2- /4 times to about times the length of the deformation zoneor section. In conventional dies in current use the die angle is about12 for high carbon steel wire, and about 16 for low carbon steel wire.

Although the wire treated in accordance with the invention is usuallycarbon steel, alloy steel or stainless steel, rod or wire of copper,aluminum and non-ferous alloys may also be treated.

Among the advantages resulting from the use of applicants improvedmethod and apparatus are better lubrication of the wire as it is drawnthrough the deformation zone resulting in a lower wire temperature and areduction of the tensile drawing or pulling force and also resulting ina more uniform flow of the metal during the deformation process,together with improved stress distribution in the wire as it passesthrough the deformation zone. These advantages provide conditions whichapproach those of hydrostatic extrusion in which no tensile drawingforce is required. Although the tension stresses are not eliminated bythe present invention the level of tension stress is below the criticalvalue which would result in internal damage to the wire. This has beenshown by density measurements and by electron-micrographs of atransverse section through the drawn wire. The longer lubricating lengthand the smaller clearance between the wire and the die wall producelubrication which is superior to that achieved in a conventional die.These conditions provide an adequate length to build up the lubricantpressure to such a high value that the lubricant is forced into thedeformation section of the die in much greater quantity than in theconventional die. This is indicated by the greater amount of charredlubricant discharged from the die with the wire. All of these factorsresult in a product that can be distinguished from wire drawn withconventional dies by its mechanical and physical properties as well asits metallurgical structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic centralvertical section illustrating the wire drawing die of the presentinvention;

FIG. 2 is a diagrammatic central vertical sectional view of aconventional die.

DETAILED DESCRIPTION Referring first to FIG. 2 which shows aconventional die as in current use the wire (not shown) is drawn throughthe die from left to right. At the entrance there is a wide curvedsection 1, referred to as a bell section, followed by an entrance angle2 which merges into the narrow end portion of bell 1. Immediatelythereafter is the deformation zone 3 the angle of which is shown as l2and next to this zone is the bearing section 4 which is cylindrical. Thelubricating zone includes bell section 1 and entrance angle 2, thepurpose of the bell section being to facilitate the entrance of apowdered lubricant, such as wire drawing soap, the wire being drawnthrough a mass of this material prior to entering the die. Indeformation zone 3 most of the reduction in the diameter of the wiretakes place, and bearing section 4 determines the final shape and sizeof the wire. The wire leaves the die through the relief section 5 whichpermits the escape of whatever charred soap may pass through the diewith the wire Referring to FIG. 1 illustrating applicants die the wirebeing drawn through the die is indicated at 6 and passes first through amass of dry powdered lubricant 8 such as soap which is supplied to acontainer 7. The

wire then enters the long lubricating section 9 of the hm same i thr h aconventional die which proi Passing successively through the deformationduces the same draft" or reduction in the diameter of Section bearingSection and back relief Section the wire. Furthermore, it has been foundthat the speed 12- It Will be not d that the die ang t a s the ngl oftravel of the wire can be increased from the convenbetween the oppositewalls of the die opening, is quite i l speed of around 600 per minute tothe speeds small, in this case 5. The charred soap 13 is shownisindicated above. In addition, the temperature of the suing from the Ity or y not, be received in wire as it leaves the die is lower and thegeneral operata suitable receptacle (not shown). The wire 6 is drawn iditi ns re su erior in every respect. through the die in a conventionalmanner as for exam- The drawing conditions for a conventional 12 die asple by attaching it to a draw bar, or by winding it about illustrated inFIG. 2 and the drawing conditions in a 5 a dr w block" or reel which ispower drivendie of the invention as illustrated in H6. 1 are shown Thelubricating section 9 and deformation section 10 in the following tableand indicate that although the deare formed by the wall 15 of afrusto-conical passageformation length has been increased in theimproved way which commences at the left where it is joined to die dueto the smaller die angle, the lubricating length the container 7 andwhich extends to the right or dis- 15 is considerably more than twice aslarge: charge end of deformation section 10. The 5 angle between theopposite sides of frusto-conical wall 15 is continuous throughout thelength of lubricating section 9 and deformation section 10. It Will beunderstood that Wire diameter, in. tonhfilhil improge giif iucfe rfs isi r this passageway is formed in a die nib of suitable matem l ff ffiffififigfififfi lubn r1al, usually tungsten carb1de, and this passagewayjoins ms I 422 968 m the cylmdncal passage 11 formmg the bearmg section,.218 .180 .322 .723 126 and the conical section 12 forming the backrelief sec- The length of the elongated space within the frustoinaddition the effectiveness of the lubricating length conical section 15and the gradual reduction in thickin the improved die is believed to begreater than in the ness of this space from the entrance end at the leftto conventional die because the bell section of the latter the beginningof the deformation zone 10 at the right die is too wide to developpressure on the powdered cause the development of sufficient pressure inthe lubricant. However, the elongated narrow space belubricant as it isdrawn along by the friction thereof tween the wire and the wall of thefrusto-conical lubriwith wire 6 to force the lubricant in quantitybetween cating section of the improved die causes the developthe wireand the walls of the deformation zone 10. ment of a very high pressuredue to the friction be- Also with wire 6 traveling at the speedspreviously intween the wire and the lubricant. dicated of from about1,000, per minute to about The following table illustratesa comparisonbetween l450l,450'per minute in cooperation with the slight the wiredrawing conditions found in conventional dies spacing of the wall of theelongated lubricating zone and in the improved die of the presentinvention.

Lubricatinglength, in. Increase in Wire dja., in. lubricating Conven-Improved length. Example Material Start Finish tional die die percent 1minim 16?? 26331111313311: :53? 3331111111 .147 .126 .360 22 1'...) 2Lggmg Wm .064 .047 .427 .032 130 d .218 .191 .332 .753 126 3 .035 .076.413 .041 120 .350 .304 .332 1.201 238 4 High strength rope wire 304 1266 .452 1. 406 210 266 234 430 1. 494 206 .406 .368 .370 1. 509 307 6Prestressed concrete strand wire. .358 .316 .413 1. 568 280 316 .230.452 1. 624 258 contribute to the feed of the lubricant into and throughThese data show that the lubricating lengths of the the elongatedlubricating zone 9 and into and through 1mproved dtes were at least l00percent longer than 1n the deformation zone 10. This speed of movementand the corresponding convennonal d1es. ln examples Nos. the narrownessof the passageway retard the lubricant l. 3 nd 4 th impr ed dles had 5angles. in examfrom moving in a direction opposite to the forward ipleN0. 6 these dtes had 9 angles. movement of the wire. These factorstogether cause the i It IS considered ev1dent that the longer lubncatmgmovement of a considerable amount of the powdered; length and thesmaller clearance between the wire and soap lubricant through the die.The size of the mass 14 the wall of the improved die explains why theimproved of charred soap which has been observed in the exdie providesbetter lubrication than a conventional die.

1 tended experimental use of the invention carried out by heseconditions provide an adequate length of the luthe inventors has beenfound to be of sizable proporbricating section to build up the lubricantpressure to tions and indicates the considerable amount of soap u h ahigh value that the lubricant is forced into the which travels throughthe die. deforming section of the die of the invention in much In suchexperimental use of the invention it has also greater quantity than inthe conventional die. been found that the pulling force requiredto beapplied By uti izing the method and apparatus of the present to wire 61ssubstantially less than when drawing a wire in n i n a cold drawn wireproduct can be produced having increased tensile strength and coredensity, also increased cohesive strength and improved ductility.

We claim:

1. A wire drawing die for reducing wire to obtain an improved wire ofsmaller diameter comprising a die member having an extendedfrusto-conical passageway therethrough, said passageway havingcontinuous walls from end to end and terminating in a short cylindricalportion at the exit end thereof, said passageway having a deformationsection adjacent said cylindrical section for reducing the diameter ofsaid wire and a lubricating section immediately preceding thedeformation section, the included angle between the walls of thelubricating section being the same as the included angle between thewalls of the deformation section, said included angle being betweenabout 5 and and the length of the lubricating section being severaltimes the length of the deformation section.

2. The method of reducing the diameter of a wire which comprises drawingit through a die having a passage therethrough including a portion offrusto-conical shape, said portion having an included angle betweenabout 5 and about 10, said portion having a minimum diameter smallerthan the diameter of the wire and a maximum diameter enough larger thanthe diameter of the wire so that the wire first engages the die at leastabout seven-tenths of the distance from the large diameter end to thesmall diameter end of said portion, and feeding a lubricant to saidlarge diameter end.

3. The method according to claim 2 wherein the wire is drawn through thedie at a speed of from about 1,000

feet per minute to about 1,450 feet per minute.

1. A wire drawing die for reducing wire to obtain an improved wire ofsmaller diameter comprising a die member having an extendedfrusto-conical passageway therethrough, said passageway havingcontinuous walls from end to end and terminating in a short cylindricalportion at the exit end thereof, said passageway having a deformationsection adjacent said cylindrical section for reducing the diameter ofsaid wire and a lubricating section immediately preceding thedeformation section, the included angle between the walls of thelubricating section being the same as the included angle between thewalls of the deformation section, said included angle being betweenabout 5* and 10*, and the length of the lubricating section beingseveral times the length of the deformation section.
 2. The method ofreducing the diameter of a wire which comprises drawing it through a diehaving a passage therethrough including a portion of frusto-conicalshape, said portion having an included angle between about 5* and about10*, said portion having a minimum diameter smaller than the diameter ofthe wire and a maximum diameter enough larger than the diameter of thewire so that the wire first engages the die at least about seven-tenthsof the distance from the large diameter end to the small diameter end ofsaid portion, and feeding a lubricant to said large diameter end.
 3. Themethod according to claim 2 wherein the wire is drawn through the die ata speed of from about 1,000 feet per minute to about 1,450 feet perminute.